RESUMO
In the present study, we identified and characterised the complete coding sequence of Babesia orientalis apical membrane antigen 1 (designated Bo-ama1); it is 1803bp in length and encodes a polypeptide of 601 amino acids (aa). The Bo-ama-1 gene product (Bo-AMA1) is predicted to be 67kDa in size and contains a signal peptide. Mature Bo-AMA1 is predicted to have one transmembrane region and a short cytoplasmic tail (C-terminal domain). The extracellular part of Bo-AMA1 has three functional domains (DI, DII and DIII) with 14 conserved cysteine residues. A Bo-AMA1 fragment containing all three of these domains (designated Bo-AMA1-DI/II/III) was cloned into the plasmid vector pET-28a and expressed as a recombinant (His-fusion) protein of 53kDa. Antibodies in the serum from a B. orientalis-infected water buffalo specifically recognised this protein in immunoblotting analysis. Rabbit antibodies raised against the recombinant protein were able to detect native Bo-AMA1 (67kDa) from erythrocytes of B. orientalis-infected water buffalo. Bo-AMA1 is a new member of the AMA1 family and might be a good antigen for the specific detection of antibodies produced in B. orientalis infected cattle. This protein is likely to play critical roles during host cell adherence and invasion by B. orientalis, as the AMA1s reported in other organisms such as Plasmodium falciparum and Toxoplasma gondii. Further research is required to explore the biological functions of this protein and to determine whether its immunisation can induce protective effects in water buffalo against B. orientalis infection.
Assuntos
Antígenos de Protozoários/imunologia , Apicomplexa/imunologia , Babesia/imunologia , Babesiose/parasitologia , Búfalos/parasitologia , Sequência de Aminoácidos , Animais , Antígenos de Protozoários/genética , Apicomplexa/genética , Babesia/genética , Sequência de Bases , DNA de Protozoário/genética , Expressão Gênica , Proteínas de Membrana/genética , Proteínas de Membrana/imunologia , Dados de Sequência Molecular , Filogenia , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Proteínas Recombinantes , Alinhamento de SequênciaRESUMO
Mycoplasma suis, the causative agent of porcine infectious anemia, causes large economic losses to the swine industry worldwide. A questionnaire-based survey was conducted in 69 pig farms in Hubei Province, China, from November 2011 to August 2013 to ascertain the prevalence and associated risk factors of M. suis. Four thousand and four blood samples from pigs of all the age groups were tested for M. suis antibodies using the established rMSG1-ELISA assay. Among these 4004 samples, 1615 blood samples from multiparous sows were examined to identify the association between seroprevalence and different seasons. Information on risk factors collected from farmers or attending veterinarians was recorded on a pre-designed questionnaire. The overall test seroprevalence of M. suis infection at the animal level was 31.9% (1277/4004; 95% CI: 30.5%, 33.4%), whereas at the farm level, this value was 95.65% (66/69; 95% CI: 87.8%, 99.1%). The seroprevalence of M. suis was higher in replacement gilts (40.6%; 95% CI: 35.1%, 46.3%), multiparous sows (48.2%; 95% CI: 45.8%, 50.7%) and boars (44.4%; 95% CI: 34.5%, 54.8%), as compared to piglets (13.0%; 95% CI: 9.4%, 17.3%), weaned-piglets (10.8%; 95% CI: 8.9%, 13.0%), and growing-finishing pigs (25.0%; 95% CI: 22.0%, 28.3%). In terms of seasons, the prevalence of M. suis in pigs was significantly higher in summer (65.3%; 95% CI: 61.0%, 69.5%) and autumn (65.0%; 95% CI: 59.0%, 70.6%) compared to spring (30.1%; 95% CI: 26.0%, 34.4%) and winter (36.4%; 95% CI: 31.4%, 41.5%). Farm-level risk factors were identified by multivariable logistic regression analysis. The associated factors retained in the final multivariable logistic regression model were drug treatment, presence of mosquitoes and flies, and frequency of disinfection. Drug treatment (OR=0.24; 95% CI: 0.07, 0.88; P=0.031) and frequency of disinfection (OR=0.23; 95% CI: 0.06, 0.90; P=0.035) were protective factors, and the presence of mosquitoes and flies (OR=5.994; 95% CI: 1.56, 23.00; P=0.009) was a risk factor for M. suis infection on farms. The results of the present study provide the first insight into the impact of associated determinants on M. suis infection in central China.